Peak expiratory flow data from 17 members of Bland's family, taken with two different instruments, each twice. This data is for explanatory use only. Columns 1 and 2 were measured with the "Wright" peak flow meter, columns 3 and 4 with the "Mini Wright" peak flow meter. These are the data behind fig. 1, fig. 2 and fig. 6 of the original paper and these can be easily reconstructed